Unsymmetrical esters of N-substituted 1,4-dihydropyridine 3,5-dicarboxylic acid

ABSTRACT

Unsymmetrical esters of N-substituted 4-substituted-1,4dihydropyridine 3,5-dicarboxylic acid optionally substituted by lower alkyl groups in the 2- and 6-positions are cardiovascular agents. The compounds, of which 1,2,6-trimethyl-4-(3&#39;&#39;nitrophenyl)-1,4-dihydropyridine 3,5-dicarboxylic acid 3-methyl5-ethyl ester is a typical example, can be prepared (A) through condensation of an ylidene- Beta -ketocarboxylic acid ester, with a Beta -ketocarboxylic acid ester and an amino or salt thereof, or with an enamino carboxylic acid ester or (B) through condensation of an aldehyde, an enamino carboxylic acid ester and a Beta -ketocarboxylic acid ester.

United States Patent n91 Meyer et al.

[ UNSYMMETRICAL ESTERS OF N-SUBSTITUTED 1,4-DIHYDROPYRIDINE 3,5-DICARBOXYLIC ACID [75] Inventors: Horst Meyer; Friedrich Bossert,

both of Wuppertal-Elberfeld; Wulf Vater, Opladen; Kurt Stoepel, Wuppertal-Vohwinkel, all of Germany [73] Assignee: Bayer Aktiengesellschaft, Germany [22] Filed: Feb. 28, 1973 [21] Appl. No.; 336,605

[30] Foreign Application Priority Data Sept. 12 i972 Germany 22l0672 [52] US. Cl... 260/2943; 260/2564 N, 260/287 R; 260/294.8 C; 260/294.8 D; 260/294.8 F;

260/2948 G; 260/2955 R; 260/2955 B;

[5 [1 Int. Cl. C07d 31/36; C07d 31/46 [58] Field of Search 260/2948 F, 294.8 G, 294.9, 260/2955 R 51 May 13, 1975 [56] References Cited UNITED STATES PATENTS 3,799.936 3/!974 Meyer et al 260/2956 R Primary Examiner-Alan L. Rotman [57] ABSTRACT Unsymmetrical esters of N-substituted 4-substituted- 1,4-dihydropyridine 3,5-dicarboxylic acid optionally substituted by lower alkyl groups in the 2- and 6- positions are cardiovascular agents. The compounds, of which l,2,6-trimethyl-4-( 3 '-nitrophenyl)- l ,4- dihydropyridine 3,5-dicarboxylic acid 3-methyl-5- ethyl ester is a typical example, can be prepared (A) through condensation of an ylidene-B-ketocarboxylic acid ester, with a B-ketocarboxylic acid ester and an amino or salt thereof, or with an enamino carboxylic acid ester or (B) through condensation of an aldehyde, an enamino carboxylic acid ester and a B-ketocarboxylic acid ester.

25 Claims, No Drawings UNSYMMETRICAL ESTERS OF N-SUBSTITUTED l,4-DIHYDROPYRIDINE 3,5-DICARBOXYLIC ACID The present invention relates to certain new unsymmetrical N-substituted l ,4- dihydropyridinedicarboxylic acid esters, to processes for their production, and to their use as coronary and anti-hypertensive agents.

It has already been disclosed that N-alkyl l,4- dihydropyridines are obtained by reaction of l,5- diketones with alkylamines (Merz, Richter. Arch. Pharm. 275, 294 (1937). A known variant of this pro cess consists in the reaction of aldehydes with B-diearbony] compounds and amine hydrochlorides according to German Offenlegungschrift 1,923,990. Symmetrical l,4-dihydrpyridine derivatives were produced by these methods. Until the present invention, it has not been possible to produce unsymmetrical esters of the N-substituted l,4-dihydropyridines and such esters have hitherto not been disclosed.

The present invention relates to unsymmetrical 1,4- dihydropyridinecarboxylic acid esters of the general formula:

in which R is mono-, dior trisubstituted phenyl, in which the substituents are selected from the group consisting of nitro, cyano, azido and S(O),,-lower alkyl, wherein n =0, l or 2, lower alkyl, lower alkoxy and halo, the total number of said substituents being not more than 3 and at least one of said substituents being nitro, cyano, azido or S(O),,-lower alkyl; or R is an aromatic ring system selected from the group consisting of naphthyl, quinolyl and isoquinolyl; or R is a heterocyclic ring system selected from the group consisting of pyridyl, pyrimidyl, thenyl, fury] and pyrryl, said aromatic ring system and said heterocyclic ring system being unsubstituted or substituted by at least one lower alkyl, lower alkoxy or halo;

R and R independent of the other, is hydrogen or lower alkyl;

R and R are different from one another and are lower alkyl, lower alkenyl, lower alkynl, lower alkoxy(]ower alkyl) or lower cycloalkyl, unsubstituted or substituted by hydroxy;

R is lower alkyl or benzyl.

The term lower alkyl denotes a univalent saturated branched or straight hydrocarbon chain containing from l to 6 carbon atoms as, for example, methyl and hexyl.

The term lower alkenyl denotes a univalent branched or straight hydrocarbon chain containing from 2 to 6 carbon atoms and ethylenic unsaturation as, for example, vinyl and 4-hcxenyl.

The term lower alkynyl denotes a univalent branched or straight hydrocarbon chain containing from 2 to 6 carbon atoms and acetylenic unsaturation as, for example, ethynyl and S-hexynyl.

The term lower alkoxy denotes a straight or branched hydrocarbon chain bound to the remainder of the molecule through an ethereal oxygen atom as, for example, methoxy and hexoxy.

The term halogeno denotes the substituents fluoro, chloro, bromo and iodo.

The term lower cycloalkyl denotes a univalent cyclic hydrocarbon ring having 3 to 6 carbon atoms, as for example, cyclopropyl, cyclobutyl, cyclopentyl and cyclohexy], and the like.

As indicated, the present invention also pertains to the physiologically acceptable non-toxic acid addition salts of these basic compounds. Such salts include those derived from organic and inorganic acids such as, without limitation, hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid, methane sulphonic acid, acetic acid, tartaric acid, lactic acid, succinic acid, citric acid, malic acid, maleic acid, sorbie acid, aconitic acid, salicyclic acid, phthalic acid, embonie acid, enanthic acid, and the like.

The compounds of the present invention can exist as optical isomers and both the racemates of these isomers and the individual isomers themselves are within the scope of the present invention. The racemates can be separated into their individual isomers through the well-known technique and forming diastereoisomeric salts with optically active acids.

In the general formula I, above, the present invention may be more particularly defined as follows:

R is phenyl radical substituted by l or 2 nitro, especially one nitro, or by one cyano, azido or S(O)"- lower alkyl, where n is 0 or 2, particularly of l to 4 carbon atoms, and which may also be substituted by lower alkyl or lower alkoxy, particularly of l to 4 carbon atoms and alkyl or lower alkoxy, particularly of l to 4 carbon atoms and more particularly of l or 2 carbon atoms, and/or by halogen, particularly chlorine or bromine, with the total number of the substituents being at most 3, preferably 2, or R is naphthyl, quinolyl, isoquinolyl, thenyl or fury], which is unsubstituted or substituted by lower alkyl or lower alkoxy, particularly of l to 4 carbon atoms or by chlorine or bromine;

R and R are hydrogen or lower alkyl, particularly of l to 4 carbon atoms, and more particularly of l or 2 carbon atoms;

R and R are different from one another and are lower alkyl, lower alkenyl, lower alkynyl, lower al koxy(lower alkyl), particularly of up to 4 carbon atoms in each moiety, or cyclohexyl, which may be substituted by hydroxy; and

R is lower alkyl, particularly of l to 4 carbon atoms, and more particularly of l to 3 carbon atoms, or benzyl.

The new compounds may be prepared as follows:

a. a ylidene-B-ketocarboxylic acid ester of the general formula:

COR

RCH C ODOR is reacted with a B-ketocarboxylic acid ester of the general formula:

R CoCH COOR and with an amine of the general formula;

R NH

or a salt thereof, if appropriate with intermediate isolation of the N-substituted enaminocarboxylic acid ester of the general formula:

If 3-nitrobenzaldehyde. acetoacetic acid ethyl ester and N-methylaminocrotonic acid isopropyl ester are used as the starting materials, the following equation illustrates Process Variant (b):

mica 2 COOCH(CH 2 CH 3 CH The starting materials used to prepare the compounds of the invention are known or can readily be produced by known methods:

The ylidene-B-ketocarboxylic acid esters are known or can be produced by known methods (org. Reactions XV, 204 ff, (1967)).

As examples there may be mentioned:

3 4 R -C=CH 00R c Ylidene-B-ketocarboxylic acid esters l 5 NHR 2'-nitrobenzylldeneacetoacetic acid methyl ester, or 2'-nitrobenzylideneacetoacetic acid ethyl ester, b. an aldehyde of the general formula 3'-nitrobenzylideneacetoacetic acid ethyl ester.

RCHO 3'-nitrobenzylideneacetoacetic acid methyl ester,

3'-nitrobenzylideneacetoacetic acid isopropyl ester, is reacted with an enaminocarboxylic acid ester of the 3'-nitrobenzylideneacetoacetic acid allyl ester general formula: 3'-nitrobenzylideneacetoacetic acid propargyl ester.

2 3'-nitrobenzylideneacetoacetic acid B-methoxy-ethyl R -C:CHC00R t" l 3'-nitr0benzy]ideneacetoacetic acid cyclohexyl ester 5 3-nitrobenzylidenepropion lacetic acid eth l ester, NHR y y I 2'-cyanobenzylideneacetoacetic acid methyl ester 311d 11 ie'kfilocarboxyllc acid gstel' of the general 2'-cyanoben2ylideneacetoacetic acid ethyl ester, mu a 2'-cyanobenzylideneacetoacetic acid propyl ester,

R3COCH2COOR4 2 -cyanobenzylideneacetoacetic acid B-n- I I I propoxyethyl ester, in water or an inert organic solvent; in which R, R! R 4'-nitrobenzylidengacetoacetic id h l ester R4 and R5 are defined 3'-cyanobenzylideneacetoacetic acid methyl ester, The two modes (a) and (b) de b abcfve 0f 4-cyanobenzylideneacetoacetic acid ethyl ester, fecting the process of the invention Wlll hereinafter be 3' nm0 4' ch10mbenzyiideneacetoacetic acid tinny] referred to as Process Variants (a) and (b). est,

If 3i'nrobenzylldeneacetoaceilc F"? methyl ester 3'-nitro-6'-chlorobenzylideneacetoacetic acid ethyl and either N-methylaminocrotonic acid isopropyl ester ester or acetoacetic acidisopropyl ester and methylamine 3I nitro 4l methoxybenzylideneacemacenc acid are used as the starting materials, the course of the remethyl ester action of Process Variant (a) can be represented by the 2r nitro 4i mgthoxvbenzylideneacctoacetic acid following equation: methyl ester CO0CH( H COOC coo CH3 2 +1 0 5 E 0 l l 11 H COOC jc 3 3 H C 0 HH CH 2'-cyano-4-methylbenzyli neac ac i acid ethyl The N-substituted enaminocarboxylic acid esters are ster. known or can be produced by known methods (A. C. 4 methylmercaptobenzylideneacetoacetic acid ethyl Cope, J.A.C.S, 67, 101 7 (l945)).

ester. As examples there may be mentioned: 2'-methylmercaptobenzylideneacetoacetic acid I methyl ester NSubstituted enaminocarboxyllc acid esters 2'-sulphinylmethylbenzylideneacetoacetic acid iso- B-N-Methylaminocrotonic acid methyl ester,

propyl ester, B-N-methylaminocrotonic acid ethyl ester, 2'-sulphonylmethylbenzylideneacetoacetic acid ethyl B-N-methylaminocrotonic acid isopropyl ester,

ester, B-N-ethylaminocrotonic acid ethyl ester, (l'-naphthylmethylidene)-acetoacetic acid methyl B-N-isopropylaminocrotonic acid methyl ester,

ester, B-N-methylaminocrotonic acid B-methoxyethyl es- 2'-ethoxy-( l '-naphthylmethylidene )-acetoacetic ter,

acid ethyl ester, B-N-methylaminocrotonic acid cyclohexyl ester,

' B-N-methylamino-B-ethylacrylic acid ethyl ester and B-N-benzylaminocrotonic acid ethyl ester.

The aldehydes of general formula RCHO are known or can be produced by known methods (E. Mosettig,

5 '-bromo-( l '-naphthylmethylidene )-acetoacetic acid methyl ester,

(2'-quinolyl)-methylideneacetoacetic acid ethyl ester,

(8'-quinolyl)-methylideneacetoacetic acid methyl Reactions VIII esmr As examples there may be mentioned: (l'-isoquinolyll-methylideneacetoacetic acid ethyl or 4'Nftrlobenzaldehyde ester, 2,4- or 2,6-dm1trobenzaldehyde, (3'-isoquinolyl )-methylideneaeetoacetic acid isopro- 2'"itro'"bmmobenzaldehydet pyl ester, 2-nitro-3-methoxybenzaldehyde, a-pyridylmethylideneaeetoacetic acid methyl ester, 2-nitro-3-methoxy-6-chlorobenzaldehyd t a-pyridylmethylideneacetoacetic acid ethyl ester, -m m-4-m h y z y a-pyridylmethylideneacetoacetic acid cyclohexyl es- 3-nitro-6-chlorobenzaldehyde,

ter, 2-, 3- or 4-cyanobenzaldehyde, B-pyridylmethylideneacetoacetic acid B-ethoxyethyl 3O 01-, B- or y-pyridinaldehyde. ester, fi-methylpyridin-Z-aldehyde, 6-methyl-a-pyridylmethylideneacetoacetic acid ethyl pyrimidin-S-aldehyde,

4,6-dimethox -p rimidin-S-aldehyde, Y 5' 4 Y-( 'py y l' Z-methylmercaptobenzaldehyde. methylideneacetoacetic acid ethyl ester, z methylsulphonylbenZaldehyde (2'-thenyl)-methyl1deneacetoacetic acid ethyl ester, z methylsulphinylbenzaldehyde 2' furfurylideneacetoacetic acid ethyl ester. 1- d z-naphthaldehydes, (2 rryl )-methylideneacetoacetic acid methyl ester 5 br0mO 1maphthaldehydg and I Z-ethoxy-l-naphthaldehyde, a-pyridylmethylidene propionylacetic acid ethyl es- 4 methy]LnaPhthaldehYde quinolin-2-, 3-, 4-, 5-, 6-, 7- and 8-aldehydes, The B-ketocarboxylic acid esters are known or can isoquinolin l and 3 aldehydes be produced by known methods (Phol and Schmidt, f

I uran-Z-aldehyde, U.S. Pat. No. 2,351,366 (1940), ref. in Chemical Abthio hen 2 aldeh dc and stracts 1944, 5224 p y pyrrol-2-aldehyde.

Possible solvents for use in the process of the invent on are water and all inert organic solvents. Preferably, B-Ketocarboxylic acid esters the solvents are alcohols, such as ethanol and methanol, ethers, such as dioxane and diethyl ether, glacial acetic acid, dimethylformamide, dimethylsulphoxide, acetonitrile and pyridine.

The reaction temperatures can be varied within a substantial range. In general, the reaction is carried out As examples there may be mentioned:

Formylacetic acid ethyl ester, acetoacetie acid methyl ester,

acetoacetic acid ethyl ester,

acetoacetic acid propyl ester,

acetoacetic acid isopropyl ester,

acctoacetic id 5-b ester, at between 20 and 200C, preferably at the boiling acetoacetic acid butyl ester, P lr 0f th l ent.

acetoacetic acid (aor [3-)methoxyethyl ester, The reaction can be carried out under normal presa emacetic acid (01- or B-)pr0poxyethyl ester, sure but also at elevated pressure. In general, normal acctoacetic acid (aor B-)hydroxyethyl ester, pressure is used.

acetoacetic acid allyl ester, In carrying out the process according to the invenacetoacetic acid propargyl ester, tion, the substances participating in the reaction are acetoacetic acid cyclohexyl ester, each employed in approximately stoichiometric p pi nylu i acid e hyl r, amounts, except that in Process Variant (a), the amine butyrylacetic acid methyl ester, and or its salt which is used is appropriately added in an exisobutyrylacetic acid ethyl ester. cess of l to 2 mols.

The amines Of general formula R NHQ ill C known. ompgunds 0f the invention are:

As examples there y be memlOnedi l-methyl-4-(2'-nitrophenyl)-l,4-dihydropyridine- Methylamlneethylamlnfi P Pl P PY 3,5-dicarboxylic acid 3-methyl-ester-5-isopropyl mine, butylamine, isobutylamine and benzylamine. ester l.2,6-trimethyl-4-( 2-nitrophenyl )-l ,4-

dihydropyridine-3,5-dicarboxylic acid 3-methylester-S-isopropyl-ester.

l.2,6-trimethyl-4-( 3'-nitrophenyl)-l ,4

dihydropyridine-3,S-dicarboxylic acid 3-methylcster 5-ethyl-ester.

l,2,6-trimethyl-4-( 3-nitrophenyl)-l ,4-

dihydropyridine-3,5-dicarboxylic acid 3-ethylester-5-isopropyl-ester.

l,2,6-trimethyl-4-( 3 '-nitrophenyl)- l .4-

dihydropyridine-3,S-dicarboxylic acid 3-ethyl- 3-ethyldihydropyridine-3,S-dicarboxylic acid 3-ethylester-S-allyl-ester. l.2,6trimethyl-4-(2'-cyanophenyl)-1,4-

dihydropyridine-3,S-dicarboxylic acid 3-ethylester-S-isopropyl-ester.

l ,6-dimethyl-2-ethyl-4-(2'-cyanophenyl)-1,4-

dihydropyridine-3,S-dicarboxylic acid 3-ethyl-ester-5-methyl-ester. l-benzyl2,6-dimethyl-4-(2-cyanophenyl)-1,4-

dihydropyridine-3,S-dicarboxylic acid 3methylester-S-ethyl-ester.

l,2,6-trimethyl-4-( 3 '-nitro-6'-chlorophenyl )-l ,4-

dihydropyridine-3,S-dicarboxylic acid 3-ethylester-S-isopropyl-ester.

l ,2,6-trimethyl-4-( 3 '-nitro-6'-chlorophenyl)- l ,4-

dihydropyridine-3,5-dicarboxylic acid 3-ethylestcr-5-B-methoxyethylester.

l,2,6-trimethyl-4-(furyl-2 )-l ,4-dihydropyridine-3 ,5-

dicarboxylic acid 3-methyl-ester-5-ethyl-ester. l-benzyl-2,6-dimethyl-4-(furyl-2')-l,4-

dihydropyridine-3,5-dicarboxylic acid 3-methylester-S-isopropyhester.

As noted above, the compounds of the present invention demonstrate the ability to reduce blood pressure and to effect a dilation of the coronary vessels. They can accordingly be used where either or both of these effects are desired. Thus upon parenteral, oral or sublingual administration. the compounds produce a distinct and long lasting dilation of the coronary vessels which is intensified by a simultaneous nitrite-like effect of reducing the load on the heart. in their strength of action, the compounds of the invention are superior to the known symmetrical N-substituted dihydropyridinedicarboxylic acid esters. The effect on heart metabolism is thus one of energy saving. In addition, the compounds lower the blood pressure of normotonic and hypertonic animals and can thus be used as antihypertensive agents. These properties can be conveniently observed in well known laboratory models. Thus, for example, the coronary vessel dilation effeet of the compounds of the invention was compared with the action of Pcrsantin by measuring the rise in oxygen saturation in the coronary sinus in the narcotized, heart-catheterized dog, with the results reported in Table l, below.

Table l Compound Dose mg/ 0 Rise 2 Reversion kg. time 3 Example 2 0.01 3i 3.5 Example 3 0.1 39 6 Example 6 0.05 39 4 Persantin 0.3 23 l-Z Notes Dose ghen in mg/kg. body vicight. administered intravenously; O 2 rise gi\cn as i rise in oxygen saturation; Reversion time given is time in hours for reversion to the initial value.

The hypotensive activity of the present compounds can be observed by measuring the blood pressure of hypertensive rats following administration of the compounds. Table ll below demonstrates the lowest dose which results in at least a 15 mm Hg reduction in blood pressure and such animals.

Table ll Compound Peroral Dose (mg/kg) Example 1 0.3 Example 2 L0 Example 3 0.3 Example 6 0.3

The toxicity of the present compounds is favorable, as demonstrated by the data in Table lll below, which reports the LD as measured on mice by peroral administration.

In addition to the effect on blood pressure and coronary vessels, the compounds also lower the excitability of the stimulus formation and excitation conduction system within the heart so that an antifibrillation action is observed at therapeutic doses. The tone of the smooth muscle of the vessels is also greatly reduced. In addition, a strong muscular-spasmolytic action is manifested in the smooth muscle of the stomach, the intestinal tract, the urogenital tract and the respiratory systern. Finally, there is some evidence that the compounds influence the cholesterol level and lipid level of the blood. These effects complement one another and the compounds are thus highly desirable as pharmaceutical agents to be used in the treatment of hypertension and conditions characterized by a constriction of the coronary blood vessels.

Pharmaceutical compositions for effecting such treatment will contain a major or minor amount, e.g. from 0.1 to 99.5 percent, preferably from 0.5 to percent, of at least one compound of the invention in combination with a pharmaceutical carrier, the carrier comprising one or more solid. semi-solid or liquid diluent, filler and formulation adjuvant which is non-toxic, inert and pharmaceutically acceptable. Such pharmaceutical compositions are preferably in dosage unit form; i.e. physically discrete units containing a predetermined amount of the drug corresponding to a fraction or multiple of the dose which is calculated to produce the desired therapeutic response. The dosage units can contain one, two, three. four or more single doses or, alternatively, one-half, third or fourth ofa single dose. A single dose preferably contains an amount sufficient to produce the desired therapeutic effect upon administration at one application of one or more dosage units according to a predetermined dosage regimen, usually a whole, half. third or quarter of the daily dosage administered once, twice, three or four times a day. Other therapeutic agents can also be present.

Although the dosage and dosage regimen must in each case be carefully adjusted, utilizing sound profes sional judgment and considering the age, weight and condition of the recipient, the route of administration and the nature and gravity of the illness, generally the daily dose will be from about 0.001 to about l mg/kg, preferably 0.002 to l mg/kg, when administered parenterally, and from about 0.05 to about 50 mg/kg, preferably 0.5 to 10 mg/kg, when administered orally. In some instances a sufficient therapeutic effect can be obtained at lower doses while in others, larger doses will be required. Administration is preferably parenterally or perorally, and more preferably by intravenous or perlingual routes.

Oral administration can be effected utilizing solid and liquid dosage unit forms such as powders, tablets, dragees, capsules, granulates, suspensions, solution. and the like.

Powders are prepared by comminuting the compound to a suitable fine size and mixing with a similarly comminuted pharmaceutical carrier such as an edible carbohydrate as for example starch. lactose, sucrose, glucose or mannitol. Sweetening, flavoring, preservative, dispersing and coloring agents can also be present.

Capsules are made by preparing a powder mixture as described above and filling formed gelatin sheaths. Glidants and lubricants such as colloidal silica, talc, magnesium stearate, calcium stearate or solid polyethylene glycol can be added to the powder mixture before the filling operation. A disintegrating or solubilizing agent such as agar-agar, calcium carbonate or sodium carbonate can also be added to improve the availability of the medicament when the capsule is ingested.

Tablets are formulated, for example, by preparing a powder mixture, granulating or slugging, adding a la bricant and disintegrant and pressing into tablets. A powder mixture is prepared by mixing the compound, suitably comminuted, with a diluent or base as described above, and optionally with a binder such as carboxymethyl cellulose, an alginate, gelatin, or polyvinyl pyrrolidone, a solution retardant such as paraffin, a resorption accelerator such as a quaternary salt and/or an absorption agent such as bentonite, kaolin or dicalcium phosphate. The powder mixture can be granulated by wetting with a binder such as syrup, starch paste, acacia mucilage or solutions of cellulosic or polymeric materials and forcing through a screen. As an alternative to granulating. the powder mixture can be run through the tablet machine and the resulting imperfectly formed slugs broken into granules. The granules can be lubricated to prevent sticking to the tablet forming dies by means of the addition of stearic acid, a stearate salt,

talc or mineral oil. The lubricated mixture is then compressed into tablets. The medicaments can also be combined with free flowing inert carriers and compressed into tablets directly without going through the granulating or slugging steps. A clear or opaque protective coating consisting of a scaling coat of shellac, a coating of sugar or polymeric material and a polish coating of wax can be provided. Dyestuffs can be added to these coatings to distinguish different unit dosages.

Oral fluids such as solutions, syrups and elixirs can be prepared in dosage unit form so that a given quantity contains a predetermined amount of the compound. Syrups can be prepared by dissolving the compound in a suitably flavored aqueous sucrose solution while elixirs are prepared through the use of a non-toxic alcoholic vehicle. Suspensions can be formulated by dispersing the compound in a non-toxic vehicle. Solubilizers and emulsifiers such as ethoxylated isostearyl alcohols and polyoxyethylene sorbitol esters, preservatives, flavor additives such as peppermint oil or saccharin, and the like can also be added.

Where appropriate, dosage unit formulations for oral administration can be microencapsulated. The formulation can also be prepared to prolong or sustain the release as, for example, by coating or embedding particulate material in polymers, wax, or the like.

Parenteral administration can be effected utilizing liquid dosage unit forms such as sterile solutions and suspensions intended for subcutaneous, intramuscular or intravenous injection. These are prepared by suspending or dissolving a measured amount of the compound in a non-toxic liquid vehicle suitable for injection such as an aqueous or oleaginous medium and sterilizing the suspension or solution. Alternatively, a measured amount of the compound is placed in a vial and the vial and its contents sterilized and sealed. An ac companying vial or vehicle can be provided for mixing prior to administration. Non-toxic salts and salt solutions can be added to render the injection isotonic. Stabilizers, preservatives and emulsifiers can also be added.

The following Examples will serve to further typify the nature of the present invention through the presentation of specific embodiments. These Examples should not be construed as a limitation on the scope of the invention since the subject matter regarded as the invention is set forth in the appended claims.

H COOC 3 I I COOC H 3 I CH CH3 l ,2,6trimethyl-4-( 3 -nitrophenyl )-l ,4- dihydropyridine-3,S-dicarboxylic acid 3-methyl-ester- S-ethyI-ester of melting point l00C (ethyl acetate/petroleum ether) was obtained by boiling a solution of 249g of 3'-nitrobenzylideneacetoacetic acid methyl ester and l4.3g of N-methylaminocrotonic acid ethyl ester in ml of glacial acetic acid for 8 hours.

Yield 49 percent of theory.

EXAMPLEZ 3 ooc I COOCH(CH 3C cl 3 After heating a solution of 24.9g of 3'- nitrobenzylideneacetoacetic acid methyl ester, l4.4g of acetoacetic acid isopropyl ester and 7.0g of methylamine hydrochloride in 150 ml of pyridine for 4 hours, 1,2 ,6-trimethyl-4-( 3 '-nitrophenyl )-l ,4- dihydropyridine-3,S-dicarboxylic acid 3 methyl-ester- 5-isopropyl-ester of melting point lO8l09C (from alcohol) was obtained.

Yield 59 percent of theory.

EXAMPLE 3 (Process Variant b) H H C OOC COOCH(CH H C I CH l ,2.6-trimethyl-4-( 3 '-nitrophenyl l ,4- dihydropyridine-3,5-dicarboxylic acid 3-ethyl-ester-5- isopropyl-ester of melting point l0O-lOlC (ethanol) was obtained by boiling a solution of 7.6g of 3- nitrobenzaldehyde, 7.2g of acetoacetic acid isopropyl ester and 7.2g of N-methylaminocrotonic acid ethyl ester in lSO ml of ethanol/glacial acetic acid (2:3) for.

nitrobenzylideneacetoacetic acid ethyl ester and 142g of acetoacetic acid allyl ester and 70g of methylamine hydrochloride in 200 ml of pyridine for 6 hours, 12.6-

trirnethyl-4-( 3 '-nitrophenyl l ,4-dihydropyridine-3,5-

dicarboxylic acid 3-ethyl-ester-5-allylester of melting point 65C (etherlpetroleum ether) was obtained.

Yield 38 percent of theory.

EXAMPLE 5 H C OOC COOCH H C i CH After boiling a solution of 24.3g of 2'- cyanobenzylideneacetoacetic acid ethyl ester, l l.6g of acetoacetic acid methyl ester and 7.0g of methylamine hydrochloride in lOO ml of pyridine for 4 hours, 1,2,6- trimethyl-4-(2-cyanophenyl )-l ,4-dihydropyridine-3 ,5- dicarboxylic acid 3-methyl-ester-5-ethyl'ester of melting point 175C (ethanol) was obtained.

Yield 6l percent of theory.

EXAMPLE6 H CN H C OOC COOCH CH=CH H C CH After boiling a solution of 12.2g of 2'- cyanobenzylideneacetoacetic acid ethyl ester, 7.2g of acetoacetic acid allyl ester and 4g of methylamine hydrochloride in ml of pyridine for 2 hours. l,2,6- trimethyl-4-( 2 '-cyanophenyl)-1 ,4-dihydropyridine-3,5- dicarboxylic acid 3-ethyl-ester-5-allylester of melting point lO3-l04C (ethyl acetate/petroleum ether) was obtained.

Yield 46 percent of theory.

EXAMPLE7 Cl H COOC H COOC H l l H C 1- CH l,2 6-trimethyl-4-( 6'-chloro-3 -nltrophenyl )l ,4- dihydropyridine-3,S-dicarboxylic acid 3-ethyl-ester-5- methylester of melting point 164C was obtained by heating a solution of 14.2g of 6'-chloro-3'- nitrobenzylideneacetoacetic acid methyl ester, 6.5g of acetoacetic acid ethyl ester and 4g of methylamine hydrochloride in m1 of pyridine for 4 hours.

Yield 57 percent of theory.

EXAMPLE 8 H COOC COOC H (3 H I CH 13 14 After boiling 3 Solution g After boiling a solution of 22.25; ofl2thenylidene)- furfuri'lldcnwc'lwacclic acid ethyl i-ggofilccm' acetoacetic acid ethyl ester llbg acetoacetic acid acetic acid methyl ester and 4g of methylamine hydromath est d 5 b l i h d ht id i chloride in 100 ml of pyridine for 5 hours. 1,21 5 1 pyridim f 6 hours .h Z d 4 tl'imc l'ly -4-(furyll'J'I .4dihydropyridinc-3,5- 5 (2'-thenyl)-l,4-dihydropyridino3.5-dicarboxylic acid dicarboxylic acid 3methylcster-5ethyl-ester of melt 3. rh l egtcr 5 ethyl ester of melting point ll3C ing point 103C (ethyl acetate/petroleum ether) was (8th) ubtuincri Obminfid- Yield 49 percent of theory.

Yield 6] percent of theory. wh i l i d EXAMPLE 9 it) 1. A compound of the general formula:

H R 000 coca i I R T R R5 in which R is mono-, dior trisubstituted phenyl, in which the After 'z gd ti l t Of 'i il 'l substituents are selected from the group consisting ace oace ic am e y es er, g ace oace 1c acat l ,t 1 methyl ester and 70g methylamine hydrochloride in 150 m1 pyridine for 6 hours blfi'mmeihylzldz" halo, the total number of said substituents being thenyll'gj'dicurhoxync acid ester s'ethyl not more than 3 and at least one of said substitu of melting point 1130C (when was Obmincd' ents being nitro. cyano, azido or Sl hvlower alkyl. 59 percent of them)" R' and R, independent of the other, is hydrogen or EXAMPLE 10 3O lOWtZI' lllkyil R and R are different from one another and are lower alkyl, alkenyl of 2 to 4 carbon atoms alkynyl of 2 to 4 carbon atoms lower alkoxytlower alkyll or lower cycloalkyl unsubstituted or substituted by hydroxy; R is lower alkyl or benzyl, or a pharmaceutically acceptable acid addition salt thereof. 3 I 2. The compound according to claim I. in which R 1s phenyl substituted by one or two nitro. cyano, axido or S(O),,-lower alkyl, in which n is U or 2 and said lower alkyl has 1 to 4 carbon atoms alkyl of l to 4 carbon atoms. alkoxy of l to 4 carbon atoms or halo, at least one of said substituents being said nitro cyano, azido or S(O),,-lower alkyl.

3. The compound according to claim 1, in which R and R are independently hydrogen or alkyl of l to 4 After heating a solution of 24.9g 3'- nitrobenzylideneacetoacetic acid methyl ester 1.30g acetoacetic acid ethyl ester and 150g benzylamine hy Carbon ms I I d hl id 200 1 idi f 6 ho r Lbenzyt- 4. The compound according to claim 1, in which R 2 6 di h 1 4 3 i h |).1 4 dih d ridi and R are different from one another and are alkyl of 3 5 di b 1i id 3. 3 ester 5 h l cstgr f l to 4 carbon atoms. alkenyl of 2 to 4 carbon atoms, almelting point 107C (ether) was obtained. kynyl of Z to 4 carbon atoms alkoxyflower alkyl] with yi ld 62 percent f theory 1 to 4 carbon atoms in said alkoxy and alkyl moieties or cyclohexyl, unsubstituted or substituted by hydroxy, EXAMPLE H S. The compound according to claim I, in which R is alkyl of l to 4 carbon atoms or benzyl. 6. The compound according to claim 1, in which R is nitrophenyl, halo substituted nitrophenyl cyanophenyl. halo substituted cyanophenyl said H COOC C0OC2F5 halo being chloro or bromo.

l R and R are independently hydrogen or lower alkyl R C N :5 R and R are different from one another and are 3 l 3 alkyl of l to 4 carbon atoms. alkenyi of 2 to 4 car- 65 bon atoms alkynyl of 2 to 4 carbon atoms. alkoxytlower alkyl) of l to 4 carbon atoms or lower cycloalkyl, unsubstituted or substituted by hydroxy and R is alkyl of l to 4 carbon atoms or benzyl.

7. The compound according to claim 1, in which R is nitrophenyl, nitrophenyl substituted by one or two halo selected from the group consisting of chloro, bromo and cyanophcnyl,

R and R are independently hydrogen or lowcr alkyl,

R and R are different from one another and are alkyl of l to 4 carbon atoms. alkenyl of 2 to 4 carbon atoms, alkoxyUower alkyl) of l to 4 carbon atoms or cyclohexyl, and

R is alkyl of l to 4 carbon atoms or benzyl.

8. The compound according to claim 1, which is lmethyl-4-( 2 '-nitrophenyl )-l ,4-dihydropyridine-3,5- dicarboxylic acid 3-methyl-estcr-5-isopropyl-ester.

9. The compound according to claim 1, which is L2,- 6-trimethyl-4-( 2 '-nitrophenyl )-l ,4-dihydropyridine- 3,5-dicarboxylic acid 3-methyl-3ester-5-isopropylester 10. The compound according to claim 1, which is l,- 2,6-trimcthyl-4-( 3 '-nitrophenyl )-l .4-dihydropyridine- 3,5-dicarboxylic acid 3-methyl-ester-S-ethyl-ester.

11. The compound according to claim 1, which is l,- 2,6-trimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine- 3,5-dicarboxylic acid 3-ethyl-ester-S-isopropyl-ester 12. The compound according to claim 1, which is l,- 2,6-trimethyl-4-( 3 '-nitrophenyl )-l ,4-dihydropyridine- 3,5-dicarboxylic acid 3-ethyl-ester-S-alkyl-ester.

13. The compound according to claim 1, which is l,- 2.6-trimethyl 4-( 3 '-nitrophenyl )-l ,4-dihydropyridine- 3,5-dicarboxylic acid 3-methyl-ester-5-B- mcthoxyethylester.

14. The compound according to claim 1, which is lbenzyl-2.6-dimethyl-4-( 3 '-nitrophenyl l ,4- dihydropyridine-3,S-dicarboxylic acid 3-mcthyl-ester- S-cthyl-ester.

15. The compound according to claim 1, which is l,- 2,6-trimethyl-4-( 3'-nitrophenyl l ,4-dihydropyridine- 3,5-dicarboxylic acid 3-methyl-ester-5-cyclohcxylester.

16. The compound according to claim 1, which is l,- 6-dimcthyl-2-ethyl-4-( 3 '-nitrophenyl )-l ,4- dihydropyridine-3,S-dicarboxylic acid 3-ethyl-ester-5- isopropyl-ester.

17. The compound according to claim 1, which is l,- 2.6-trimcihyl-4-( 2'-cyanophenyl )-l ,4-dihydropyridinc- 3,5-dicarboxylic acid 3-methyl-cster-5-ethyl-ester.

18. The compound according to claim 1, which is l,- 2,6-trimethyl-4-( 2 '-cyanophenyl )-l .4-dihydropyridine, 3,5-dicarboxylic acid 3-ethyl-ester-5 allylester.

19. The compound according to claim 1, which is l,- 2,6trimethyl-4-( 2-cyanophenyl )-l ,4-dihydropyridinc- 3,Sdicarboxylic acid 3-ethyl-ester-5is0propyl-ester 20. The compound according to claim 1, which is l,- 6-dimethyl-2-ethyl-4-( 2 '-cyanophenyl l ,4- dihydropyridine-3,S-dicarboxylic acid 3-ethyl-ester-5 methyl-ester.

21. The compound according to claim 1, which is lbenzyl-2,6-dimethyl-4-( 2'-cyanophenyl )-l ,4 dihydropyridine-3,5-dicarboxylic acid 3-methyl-ester- S-ethyl-ester.

22. The compound according to claim 1, which is l,- 2,6-trimethyl-4( 3 '-nitro-6'-chlorophenyl )l ,4- dihydropyridine-3,5-dicarboxylic acid 3-ethyl-ester-5- isopropyl-ester.

23. The compound according to claim 1, which is l,- 2,6-trimethyl4-( 3'-nitro-6'-chlorophenyl )'l ,4- dihydropyridine-3,S-dicarboxylic acid 3-ethyl-ester-5- B-methoxyethyl-ester.

24. The compound according to claim 1, which is l,- 2,6-trimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine- 3,5-dicarboxylic acid 3-methyl-ester-S-isopropyl-ester.

25. The compound according to claim 1, which is 1,- 2.6-trimethyl-4-( 6-chloro-3'-nitrophenyl l ,4- dihydropyridine-3,S-dicarboxylic acid 3-ethyl-ester-5- methyl-ester. 

1. A COMPOUND OF THE GENERAL FORMULA:
 2. The compound according to claim 1, in which R is phenyl substituted by one or two nitro, cyano, axido or S(O)n-lower alkyl, in which n is 0 or 2 and said lower alkyl has 1 to 4 carbon atoms, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms or halo, at least one of said substituents being said nitro, cyano, Azido or S(O)n-lower alkyl.
 3. The compound according to claim 1, in which R1 and R3 are independently hydrogen or alkyl of 1 to 4 carbon atoms.
 4. The compound according to claim 1, in which R2 and R4 are different from one another and are alkyl of 1 to 4 carbon atoms, alkenyl of 2 to 4 carbon atoms, alkynyl of 2 to 4 carbon atoms, alkoxy(lower alkyl) with 1 to 4 carbon atoms in said alkoxy and alkyl moieties or cyclohexyl, unsubstituted or substituted by hydroxy.
 5. The compound according to claim 1, in which R5 is alkyl of 1 to 4 carbon atoms or benzyl.
 6. The compound according to claim 1, in which R is nitrophenyl, halo substituted nitrophenyl, cyanophenyl, halo substituted cyanophenyl, said halo being chloro or bromo, R1 and R3 are independently hydrogen or lower alkyl, R2 and R4 are different from one another and are alkyl of 1 to 4 carbon atoms, alkenyl of 2 to 4 carbon atoms, alkynyl of 2 to 4 carbon atoms, alkoxy(lower alkyl) of 1 to 4 carbon atoms or lower cycloalkyl, unsubstituted or substituted by hydroxy, and R5 is alkyl of 1 to 4 carbon atoms or benzyl.
 7. The compound according to claim 1, in which R is nitrophenyl, nitrophenyl substituted by one or two halo selected from the group consisting of chloro, bromo and cyanophenyl, R1 and R3 are independently hydrogen or lower alkyl, R2 and R4 are different from one another and are alkyl of 1 to 4 carbon atoms, alkenyl of 2 to 4 carbon atoms, alkoxy(lower alkyl) of 1 to 4 carbon atoms or cyclohexyl, and R5 is alkyl of 1 to 4 carbon atoms or benzyl.
 8. The compound according to claim 1, which is 1-methyl-4-(2''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl-ester-5-isopropyl-ester.
 9. The compound according to claim 1, which is 1,2,6-trimethyl-4-(2''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl-3-ester-5-isopropyl-ester.
 10. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl-ester-5-ethyl-ester.
 11. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-ethyl-ester-5-isopropyl-ester.
 12. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-ethyl-ester-5-alkyl-ester.
 13. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl-ester-5- Beta -methoxyethylester.
 14. The compound according to claim 1, which is 1-benzyl-2,6-dimethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5 -dicarboxylic acid 3-methyl-ester-5-ethyl-ester.
 15. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl-ester-5-cyclohexyl-ester.
 16. The compound according to claim 1, which is 1,6-dimethyl-2-ethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-ethyl-ester-5-isopropyl-ester.
 17. The compound according to claim 1, which is 1,2,6-trimethyl-4-(2''-cyanophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl-ester-5-ethyl-ester.
 18. The compound according to claim 1, whIch is 1,2,6-trimethyl-4-(2''-cyanophenyl)-1,4-dihydropyridine, 3,5-dicarboxylic acid 3-ethyl-ester-5-allyl-ester.
 19. The compound according to claim 1, which is 1,2,6-trimethyl-4-(2''-cyanophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-ethyl-ester-5-isopropyl-ester.
 20. The compound according to claim 1, which is 1,6-dimethyl-2-ethyl-4-(2''-cyanophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-ethyl-ester-5-methyl-ester.
 21. The compound according to claim 1, which is 1-benzyl-2,6-dimethyl-4-(2''-cyanophenyl)-1,4-dihydropyridine-3,5 -dicarboxylic acid 3-methyl-ester-5-ethyl-ester.
 22. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitro-6''-chlorophenyl)-1,4-dihydropyridine-3,5 -dicarboxylic acid 3-ethyl-ester-5-isopropyl-ester.
 23. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitro-6''-chlorophenyl)-1,4-dihydropyridine-3,5 -dicarboxylic acid 3-ethyl-ester-5- Beta -methoxyethyl-ester.
 24. The compound according to claim 1, which is 1,2,6-trimethyl-4-(3''-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl-ester-5-isopropyl-ester.
 25. The compound according to claim 1, which is 1,2,6-trimethyl-4-(6''-chloro-3''-nitrophenyl)-1,4-dihydropyridine-3,5 -dicarboxylic acid 3-ethyl-ester-5-methyl-ester. 